Many types of waste are poured down drains. Fats, oils, and grease (“FOG”) are common such wastes that are present in meats, cooking and salad oils, cooking grease, lard, butter, margarine and multitude of other foodstuffs. Additionally, FOG may also refer to non-edible fats, oils, and greases.
FOG, in particular, poses a problem for sewer systems because fats, oils, and greases are largely insoluble in water and will accumulate over time in drainage pipes, as well as further down the sewer path. These accumulations may not only primarily restrict waste water flow thought the pipe, but can also secondarily restrict water flow by providing a substrate where solid waste can stick. These restrictions may build to the point where the pipe is sufficiently blocked so that waste water will back up into homes and businesses causing expensive damage and requiring further corrective actions to increase the flow of waste water. Since most buildings have a single common sewer pipe for all waste water, the results of a backup of water can be much more unpleasant than the backing up of only water from a sink.
Home and restaurant kitchens, as well as catering and institutional food services can spend thousands of dollars to repair the damage caused by the buildup of FOG. The sequela of a clogged drain can cause a home to be temporarily inhabitable and force a business to close until the sewer drain is cleared and the damage is cleaned and repaired. The advantages to keeping drains free of any build up before a blockage occurs are clear, however the most common preventative measures often include the use of corrosive chemicals that are dangerous to handle and store, and which are not environmentally sound.
The problems with FOG waste are not limited to individual buildings, municipalities also have to contend with the build up of FOG in shared sanitary sewer lines as well as in treatment plants and any other effluent transfer and storage facilities. A municipality's expenses associated with keeping the accumulation of FOG minimal through the use of physical methods can be substantial. These costs, however, are preferable to having to clean (if possible) or replace sections of sewer that have become impassible to waste water due to the severe accumulation of insoluble waste. These blockages, which are often caused by FOG, can cause a sanitary sewer overflow (an “SSO”). An SSO is not only expensive to fix and clean itself, but in the event of an SSO, the US Environmental Protection Agency may issue substantial fines to the governing municipality. Additionally, if such an overflow contaminates the drinking water supply, the resulting public health emergency will require, at the least, the issuance of a boil order, where all affected people need to boil water before consuming it. In more extreme cases, boiling may be insufficient and clean water will need to be brought in, or the people moved out, until the water is again made drinkable.
Among the methods of mitigating FOG buildup are two common physical methods: hydro-jetting and pumping. Hydro-jetting essentially involves spraying the effluent facility (such as a sewer line) with high pressure water to break up any blockages. Generally, the hydro-jetting begins at the end of the blockage most distal to the originating drain and is directed upstream, towards the most proximal end of the blockage. In this manner, loosened material drains away from the blockage. A disadvantage to hydro-jetting is that no material is removed, it is simply broken up and washed more distal to the originating drain, where it may re-aggregate into another blockage further downstream. Accumulations in municipality controlled common sewer lines or effluent facilities can effect multiple buildings and multiple drains and create problems that are much more difficult and expensive to repair than a localized blockage.
Pumping is a much different solution to the problem of FOG buildup. In pumping, FOG is pumped from a point of accumulation and then otherwise disposed. The removed FOG may be, inter alia, recycled, converted into bio-diesel, enzymatically degraded, or placed into a landfill. The costs associated with pumping, transporting the recovered FOG, and disposing it can be substantial.
A different water contaminant is known as Biochemical oxygen demand (“BOD”). BOD is a procedure used to determine the amount of oxygen needed in a sample of water to allow aerobic bacteria to break down the organic material in said sample. It is often expressed as milligrams of oxygen consumed per liter of sample after a five day incubation at 20 degree Celsius, and is used as an indirect measurement of the organic pollution in water. In typical parlance, BOD is listed as a pollutant itself, such as in the U.S. Clean Water Act, although it is actually a measurement of organic contaminants. This typical usage is used in the application.
BOD includes all organic matter found in waste water. Fallen leaves and decaying plant material are the predominant natural sources of this organic matter, however the greatest sources of BOD, at least in developed area, can be traced to human impact. Runoff of nutrients from lawn fertilizers, grass clippings, paper, food scraps pushed down a disposal, and fecal matter, all contribute to the amount of organic material found in waste water. A sample's BOD directly relates to the amount of organic waste it contains, so lower BOD values indicate a lower amount of organic waste.
The potential for damage caused by the accumulation of FOG, as well as the additional processing required for waste water heavily polluted with FOG and BOD to ensure compliance with the Federal Clean Water Act and other relevant regulations, has caused municipalities to shift costs through the use of contaminant surcharges. For businesses such as food processing facilities that expel high FOG and BOD waste water, these contaminant surcharges can total in the tens of thousands a month.
Methods of using biological materials to reduce foodstuffs and FOG in waste water are known in the art.
Australian Patent AU739218B2 discloses a composition consisting of, inter alia, bacteria and free enzymes, that will digest macerated foodstuffs in a garbage disposal unit. This composition may also be used when macerated foodstuffs are in a drain line, proximal to the garbage disposal unit.
U.S. Pat. No. 6,187,193B1 discloses a method of decomposing FOG in a grease trap apparatus. The apparatus of the '193 patent holds drainage and stirs or splashes it via a rotating impeller or a sprinkler that sprinkles drainage onto the top of the held drainage pool. Aerobic bacteria are supplied to the drainage pool and the agitation caused by the spinning impeller or sprinkler supplies the bacteria with oxygen. Waste water processed by this apparatus are then expelled to a sewer system.
U.S. Pat. No. 7,338,692B1 discloses a method of reclaiming FOG from a grease trap using a recyclable solvent so that the FOG can be further processed or disposed.
U.S. Patent application 2008/0251451 A1 discloses a method and an apparatus for treating waste in which one or more reactor vessels accepts inputs of waste and of aerobic bacteria, an aeration means aerates the waste and supports the aerobic bacteria, and the treated waste water can be removed through an outlet means.
U.S. Pat. No. 6,325,934B1 discloses a granular substance comprising bacteria and enzymes in a heavy material that releases the bacteria and enzymes over a period of between a day and two weeks an water. The granular material is made heavy so that the particles sink into accumulated sludge in the bottom of a sewage digestion chamber, in this way minimizing dilution of the active ingredients in grey water above the sludge.
U.S. Pat. No. 6,706,518B2 discloses a method and apparatus for clearing FOG in which a dry agent comprising bacteria and enzymes is incubated to form an aqueous solvent capable of cleaning and clearing FOG. After production, this solvent is placed in contact with FOG to catalyze digestion of the FOG.
U.S. Pat. No. 5,464,766 discloses a powdered product consisting of, inter alia, enzymes and bacteria that can be delivered to a site containing organic waste in order to digest such waste.
These methods may be useful, but some require specialized, and perhaps also expensive equipment, while others are best suited for removal of accumulated waste products which may not be discovered until a drainage problem is discovered. Some would not reduce the pollution in the waste water entering a sewer or the contamination surcharges that may be imposed by a municipality.